The present invention relates to motor-driven personal vehicles, particularly for patients and others who have some physical disability, but are sufficiently physically active to be able to assemble and disassemble a demountable sulky, and transfer the components to and from a vehicle trunk, or to luggage which can accompany them on an airline trip. Because conventional wheelchairs are bulky, it is not feasible to transport them in even the larger automobiles. Even when the wheelchair is of the foldable type and can be placed in a vehicle trunk, it leaves practically no room in the trunk for anything else. In the case of those wheelchairs where a motorized drive unit is attachable and detachable from the wheelchair, as disclosed in U.S. Pat. Nos. 3,921,744 and 4,503,925, the motorized drive unit, when detached, needs to be separately transported in the vehicle. Normally, the attachable drive units disclosed in the aforementioned patents provide a front wheel, driven by an electric motor which is supported on a steering post-frame assembly which further supports a battery for supplying the necessary electrical current to the electric motor, and such units are commercially available. However, to my knowledge, no seat supporting sulky vehicle which could be broken down into compact component pieces has been commercially available. One of the prime reasons has been the lack of a safe and rigid latch system which could be engaged and disengaged by hand, without the use of tolls. Latching systems of various types have been proposed for various vehicles as disclosed, for instance, in U.S. Pat. Nos. 4,452,327 and 4,203,612, but none of these vehicular latch constructions satisfy all of the necessary criteria and provide the stability which is necessary.